1. Field of the Invention
The present invention relates to an air conditioning apparatus for a vehicle, which controls a temperature of air blown toward a passenger compartment by adjusting a ratio between an amount of cool air and an amount of warm air, while decreasing a pressure loss in a ventilation system.
2. Description of Related Art
In a conventional air conditioning apparatus, an air conditioning unit including an evaporator, a heater core and an air outlet mode selecting mechanism is disposed in a front portion of a passenger compartment at an approximate center position in a left-right direction of the vehicle, and a blower unit for blowing air toward the air conditioning unit is disposed at an offset position of the air conditioning unit in the left-right direction. Warm air having passed through the heater core and cool air bypassing the heater core are mixed in an air mixing chamber, and the ratio between the amount of warm air and the amount of cool air is adjusted by an air mixing door. A defroster opening portion for blowing conditioned air toward an inner surface of a windshield of the vehicle is provided at an upper side of an air conditioning case of the air conditioning unit, a foot opening portion for blowing conditioning air toward the foot portion of a passenger in the passenger compartment is provided at a lower side of the air conditioning case, and a face opening portion for blowing conditioning air toward the head portion of the passenger in the passenger compartment is provided at an upper side of the air conditioning case.
In the conventional air conditioning apparatus, to obtain cool capacity for rapidly cooling the passenger compartment in the summer, a cool air bypass passage, the air mixing chamber and the face opening portion are communicated with each other in an approximate straight line to have a small bent portion. Therefore, in a face mode, a pressure loss of a ventilation system of the air conditioning unit can be decreased to increase the cooling capacity for the passenger compartment. Thus, the air mixing chamber is usually disposed at an upper side of the air conditioning unit (i.e., at an inlet portion of the face opening portion).
However, in the conventional air conditioning apparatus, because cool air and warm air are always mixed in the air mixing chamber even when any one of the defroster opening portion, the foot opening portion and the face opening portion are opened, the pressure loss of the ventilation system becomes large in a foot mode where the foot opening portion is opened. Because the pressure loss in the ventilation system becomes larger, the blower unit becomes larger, and air-blowing noise also becomes larger.
To overcome the above-described problem, in an air conditioning apparatus described in U.S. Pat. No. 4,791,981, an air mixing chamber is provided in each of inlet sides of the face opening portion and the foot opening portion, and the temperature of air to be blown toward the face opening portion and the temperature of air to be blown toward the foot opening portion are respectively independently controlled. However, in the air conditioning apparatus, a heating heat exchanger is disposed vertically at a downstream air side of a cooling heat exchanger, and air having passed through the cooling heat exchanger is largely bent around the heating heat exchanger. Therefore, the pressure loss in the ventilation system is also increased. Further, in the air conditioning apparatus, there is not indicated a temperature control of air blown toward a rear seat side in the passenger compartment and a pressure loss in an air passage for the rear seat side in the passenger compartment.
In view of the foregoing problems, it is a first object of the present invention to provide an air conditioning apparatus for a vehicle, which controls a temperature of air to be blown toward a passenger compartment by adjusting a ratio of an amount of cool air and an amount of warm air, while decreasing a pressure loss in a ventilation system.
It is a second object of the present invention to provide an air conditioning apparatus for a vehicle, which controls a temperature of air to be blown toward a passenger compartment by adjusting a ratio of an amount of cool air and an amount of warm air, while decreasing a size of the apparatus.
It is a third object of the present invention to provide an air conditioning apparatus for a vehicle, which can control a temperature of air to be blown toward a rear seat side in a passenger compartment, and can decrease a pressure loss in an air passage through which air is blown toward the rear seat side in the passenger compartment.
According to a first aspect of the present invention, in an air conditioning apparatus for a vehicle, air from a first bypass passage and air from a heating heat exchanger are adjusted by a first air mixing unit and are mixed in a first air mixing chamber, and the mixed air is blown toward a face opening portion or a defroster opening portion. Further, air from a second bypass passage and air from the heating heat exchanger are adjusted by a second air mixing unit and are mixed in a second air mixing chamber, and the mixed air is blown toward a foot opening portion. Thus, by respectively providing the face opening portion and the foot opening portion to be respectively adjacent to the first air mixing chamber and the second air mixing chamber, the face opening portion and the foot opening portion can be separated from each other to respectively increase the opening areas of the face opening portion and the foot opening portion. Each of a cooling heat exchanger and the heating heat exchanger is disposed in such a manner that air passes through the heat exchangers from a front side to a rear side of the vehicle, and each of the first air mixing unit and an air outlet mode selecting unit is a film member sliding in an un-down direction of the vehicle. Thus, a size of the air conditioning apparatus in a front-rear direction of the vehicle is reduced. Further, because the second air mixing chamber is provided at an immediately downstream air side of the heating heat exchanger, air having passed through the heating heat exchanger can approximately linearly flow into the second air mixing chamber at a side of the foot opening portion. Thus, an air passage for leading air toward the foot opening portion can be greatly reduced. As a result, in a face mode, the pressure loss in the air passage becomes smaller to increase the amount of air blown toward the passenger compartment; and therefore, a blower unit can be made smaller to reduce an air-blowing noise.
According to a second aspect of the present invention, in an air conditioning apparatus for a vehicle, air from a first bypass passage and air from a heating heat exchanger are mixed in a first air mixing chamber for blowing the mixed air toward a front face opening portion, air from a second bypass passage and air from the heating heat exchanger are mixed in a second air mixing chamber for blowing the mixed air toward a front foot opening portion, and air from a rear cool air passage and air from a rear warm air passage are mixed in a rear air mixing chamber provided on an extending line of a flow direction of air passing through the heating heat exchanger. The air mixed in the rear air mixing chamber is blown toward a rear opening portion. Thus, air having passed through the heating heat exchanger can approximately linearly flow into the rear air mixing chamber. As a result, the pressure loss in the rear warm air passage can be reduced to increase the amount of air blown toward a rear seat side in a passenger compartment.
Preferably, the first bypass passage and the first air mixing chamber are provided at an upper side of the heating heat exchanger, and the second bypass passage is provided at a lower side of the heating heat exchanger. Therefore, the first bypass passage and the first air mixing chamber can be linearly communicated with the face opening portion at an upper side of the heating heat exchanger, and the second bypass passage can be made proximate to the second air mixing chamber. Thus, the pressure loss in a ventilation system becomes smaller, while decreasing a size of the air conditioning apparatus.